Study On Compound Catalytic Characteris And Kinetic Analysis Of Microwave-assisted Pyrolysis Of Microalgae

Due to the increasing global demand for energy and the increasingly serious problems such as the shortage of fossil energy and environmental pollution,many scholars around the world have focused their research and development work on the exploration of other sources of energy.Biomass energy is one of the most promising new energy sources at present,and its characteristics such as renewable,zero carbon emission and rich resources can perfectly make up for the shortcomings of fossil fuels currently exposed.In recent years,the preparation of biodiesel has attracted great attention.Firstly,the conversion of biomass to biodiesel is beneficial to the storage and utilization of energy.Secondly,biodiesel has the potential to replace traditional petroleum.However,limited by the way of biomass utilization,the quality and production efficiency of biodiesel are difficult to meet the requirements of mass production and commercial use.In this paper,microwave absorber and catalyst are mixed as compound additives.The effect of different compound additives types(activated carbon mixed with Ca O(CCa compound additive),activated carbon mixed with Fe₂O₃(CFe compound additive)and graphite mixed with Fe₂O₃(GFe compound additive)),different addition amounts(5,10,15and 20%)and different mixing ratios(0:10,3:7,4:6,5:5,6:4,7:3,and 10:0)on microwave catalytic pyrolysis of Dunaliella Salina,and compared with the group without additives.The thermogravimetric characteristics and kinetics analysis of microwave-assisted catalytic pyrolysis of Dunaliella Salina under GFe compound additive were analyzed.The main conclusions are as follows:Under the action of CCa compound additive,the optimal catalytic effect on weight loss characteristic parameters of microwave pyrolysis of Dunaliella Salina was the group with20%addition amount and the mixture ratio of activated carbon:Ca O=4:6.In addition,the group under 20%addition amount with carbon:Ca O=4:6 has a synergistic effect on the maximum weight loss rate(R_p),average weight loss rate(R_a)and total weight loss(M)during pyrolysis,while the group under 20%addition amount with activated carbon:Ca O=3:7 has an inhibitory effect on these three weight characteristic parameters.Under the action of CFe compound additive,the optimal catalytic effect on the weight loss characteristic parameters of microwave pyrolysis of Dunaliella Salina was the group with 15%addition amount and the mixture ratio of activated carbon:Ca O=5:5.Under 15%addition amount,the compound additive has a synergistic effect on R_pand R_a,but has an inhibitory effect on M.Under the action of GFe compound additive,when the addition amount is 5%,the optimal catalytic effect on the temperature characteristic parameters of microwave pyrolysis of Dunaliella Salina is graphite:Fe₂O₃=3:7 group,and it has a synergistic effect on the three temperature characteristic parameters of the pyrolysis process,namely,the highest temperature(T_m),the maximum heating rate(H_m)and the average heating rate(H_a).When the addition amount is 10%,the compound additive has an inhibitory effect on T_m,H_mand H_a,among which the optimal catalytic effect for the temperature characteristic parameters of microwave pyrolysis of Dunaliella Salina is the group with graphite:Fe₂O₃=10:0.Under the action of GFe compound additive,with the increase of graphite content,the innitial pyrolysis temperature(T_i)and the temperature(T_p)corresponding to the peak weight loss rate of Dunaliella Salina decreased,while the average weight loss rate of the main stage of pyrolysis of Dunaliella Salina(R_a),comprehensive pyrolysis characteristic index(S)and solid residue(M_r)increased.According to the kinetic analysis,whether the addition amount is5%or 10%,the lowest mixing ratio of apparent activation energy(E)is graphite:Fe₂O₃=7:3.Among them,the E of group under 5%addition amount with graphite:Fe₂O₃=7:3 was 53.6k J/mol,and the E of group under 10%addition amount with graphite:Fe₂O₃=7:3p was 28.26kJ/mol.